Add new tests for macro nesting

tests/tests2/64_macro_nesting.c

@@ -0,0 +1,10 @@
+#define CAT2(a,b) a##b
+#define CAT(a,b) CAT2(a,b)
+#define AB(x) CAT(x,y)
+
+int main(void)
+{
+  int xy = 42;
+  printf("%d\n", CAT(A,B)(x));
+  return 0;
+}

tests/tests2/64_macro_nesting.expect

@@ -0,0 +1 @@
+42

tests/tests2/Makefile

@@ -78,7 +78,8 @@ TESTS =	\
  60_enum_redefinition.test \
  61_undefined_enum.test \
  62_enumerator_redefinition.test \
- 63_local_enumerator_redefinition.test
+ 63_local_enumerator_redefinition.test \
+ 64_macro_nesting.test
 
 # 30_hanoi.test -- seg fault in the code, gcc as well
 # 34_array_assignment.test -- array assignment is not in C standard